Manufacturing method and manufacturing apparatus for delamination container

ABSTRACT

In a manufacturing method for a delamination method, in a second injection molding including forming a second layer on an inner peripheral side of a first layer of a preform having a bottomed cylindrical shape, a second resin material is guided from an opening portion formed in the first layer toward the inner peripheral side of the first layer, and a locking portion protruding from the opening portion toward an outer peripheral side of the first layer is integrally formed with the second layer.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a manufacturing method and amanufacturing apparatus for a delamination container.

Description of the Related Art

Conventionally, there has been known a resin-made delamination containerhaving a two-layer structure of an inner layer and an outer layer, inwhich the inner layer is peeled from the outer layer in accordance withdischarge of contents thereof. This type of delamination container isalso referred to as a delamination bottle or an airless bottle, and isused as, for example, a container of a seasoning liquid such as soysauce or of a cosmetic liquid of cosmetic products.

At present, in the production of this type of delamination container, anextrusion blow method is generally used, and a stretch blow method isnot used as often (see JP 5267901).

For example, from the viewpoint of improving the appearance, dimensionalaccuracy, physical property strength, and the like of the delaminationcontainer and reducing the environmental load of unnecessary materials,applying a blow molding method of a one-stage hot parison type in whichan injection molding step to a blow molding step are continuouslyperformed in the production of the delamination container has beenconsidered.

However, in the delamination container, the melting point of the resinmaterial of the outer layer is often set higher than the melting pointof the resin material of the inner layer. In the injection molding stepfor molding a preform having the two-layer structure, when the resinmaterial of outer layer that is at a high temperature is injected afterthe inner layer is formed, the surface of the inner layer in contactwith the resin material of the outer layer is melted and thermallydeformed. For this reason, it is extremely difficult to manufacture adelamination container by using a blow molding method of a hot parisontype.

When the weldability between the outer layer and the inner layer is lowin the preform of the delamination container, unintended separation ormisalignment between the outer layer and the inner layer can occur. Forexample, when the core mold inserted into the preform having thetwo-layer structure is pulled out, if the inner layer is fixed to thecore mold and wound up, unintended separation or misalignment from theouter layer can occur. In addition, for example, when the preform havinga two-layer structure is blow-molded, an event can occur in which theinner layer and the outer layer slip with respect to each other, and thedelamination container is molded in a state where the outer layer andthe inner layer are misaligned.

SUMMARY OF THE INVENTION

A manufacturing method for a delamination container as an aspect of thepresent invention includes a first injection molding step ofinjection-molding a first layer of a preform having a bottomedcylindrical shape from a first resin material, a second injectionmolding step of injecting a second resin material different from thefirst resin material to form a second layer on an inner peripheral sideof the first layer, and a blow molding step of blow-molding, in a stateof having residual heat from injection molding, the preform obtained inthe second injection molding step, to manufacture the delaminationcontainer. In the second injection molding step, a second resin materialis guided from an opening portion formed in the first layer toward theinner peripheral side of the first layer, and a locking portionprotruding from the opening portion toward an outer peripheral side ofthe first layer is integrally formed with the second layer.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal section view of a preform of a firstembodiment.

FIG. 2 is a longitudinal section view of a delamination container of thefirst embodiment.

FIG. 3 is a diagram schematically illustrating a configuration of a blowmolding apparatus according to the first embodiment.

FIGS. 4A to 4C are diagrams illustrating a manufacturing process of thepreform of the first embodiment.

FIG. 5A is a diagram illustrating the vicinity of a bottom portion of afirst layer in a first injection molding unit of the first embodiment,and FIG. 5B is a diagram illustrating the vicinity of the bottom portionof the preform in a second injection molding unit of the firstembodiment.

FIGS. 6A and 6B are perspective views of a configuration example of asecond cavity mold of the first injection molding unit.

FIG. 7 is a flowchart illustrating steps of a manufacturing method forthe delamination container.

FIG. 8 is a longitudinal section view of a preform of a secondembodiment.

FIGS. 9A to 9C are diagrams illustrating a manufacturing process of thepreform of the second embodiment.

FIG. 10A is a diagram illustrating the vicinity of the bottom portion ofthe first layer in a first injection molding unit of the secondembodiment, and FIG. 10B is a diagram illustrating the vicinity of thebottom portion of the preform in a second injection molding unit of thesecond embodiment.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, an embodiment of the present invention will be describedwith reference to the drawings.

In the embodiment, for the sake of more understandable description,structures or elements other than the main parts of the presentinvention will be described in a simplified or omitted manner. Inaddition, in the drawings, the same elements are denoted by the samereference signs. To be noted, shapes, dimensions, and the like of eachelement are schematically illustrated in the drawings, and do notindicate actual shapes, dimensions, and the like.

First Embodiment

<Configuration Example of Preform>

First, a configuration example of a preform for a delamination containeraccording to a first embodiment will be described with reference to FIG.1 . FIG. 1 is a longitudinal section view of a preform 10 of the firstembodiment. The overall shape of the preform 10 is a bottomedcylindrical shape in which one end side is open and the other end sideis closed. The preform 10 includes a body portion 14 formed in acylindrical shape, a bottom portion 15 that closes the other end side ofthe body portion 14, and a neck portion 13 formed in an opening on theone end side of the body portion 14.

The preform 10 has a two-layer structure in which a second layer (innerlayer) 12 is formed on the inside of a first layer (outer layer) 11. Thefirst layer 11 and the second layer 12 are formed from differentthermoplastic resin materials by two-stage injection molding as will bedescribed later. The first layer 11 is formed from a synthetic resinhaving excellent moldability and transparency. In contrast, the secondlayer 12 is formed from a synthetic resin having a property (forexample, moisture barrier property, gas barrier property, heatresistance, and chemical resistance) for stably storing the contents ofthe container and suppressing deterioration (oxidation). In addition,the resin material of the first layer 11 is selected to have a meltingpoint higher than that of the resin material of the second layer 12.

Hereinafter, the resin material of the first layer 11 will be alsoreferred to as a first resin material, and the resin material of thesecond layer 12 will be also referred to as a second resin material.

The combination of the first resin material and the second resinmaterial can be appropriately selected according to the specification ofthe delamination container. Specific examples of the material includepolyethylene terephthalate (PET), polyethylene naphthalate (PEN),polycyclohexanedimethylene terephthalate (PCTA), Tritan ((registeredtrademark): co-polyester manufactured by Eastman Chemical),polypropylene (PP), polyethylene (PE), polycarbonate (PC),polyethersulfone (PES), polyphenylsulfone (PPSU), polystyrene (PS),cyclic olefin polymer (COP/COC), polymethyl methacrylate (PMMA): acrylicresin, polylactic acid (PLA), and the like.

For example, the first resin material is polyethylene terephthalate(PET), and the second resin material is polypropylene (PP). The meltingpoint of PP is about 160 to 170° C., and the melting point of PET ishigher than the melting point of PP and is about 245 to 260° C.

In the body portion 14 of the preform 10, a ratio (t1/t2) of a thicknesst1 of the first layer 11 to a thickness t2 of the second layer 12 ispreferably 1.5 or more. The thickness ratio is preferably 3.0 or lessfrom the viewpoint of ensuring the transparency of the delaminationcontainer to be molded.

In addition, in the bottom portion 15 of the preform 10, an openingportion 16 penetrating the first layer 11 is formed at the center of thebottom portion of the first layer 11. The opening portion 16 of thefirst layer 11 is closed from the inside by the second layer 12. On theouter side of the first layer 11, the second layer 12 has a lockingportion 19 protruding outward from the opening portion 16 in the radialdirection. The locking portion 19 may be annularly formed along the edgeof the opening portion 16, or a plurality of the locking portions may beformed at intervals in the circumferential direction.

In addition, a recess portion 17 for forming an air introduction hole inthe delamination container is formed in the bottom portion 15 of thepreform 10. The recess portion 17 has, for example, a circular crosssection, and is formed at least at one position spaced apart in theradial direction from the center of the bottom portion 15 of the preform10, but a plurality of recess portions 17 may be formed along thecircumferential direction of the bottom portion 15. The depth of therecess portion 17 in the thickness direction of the preform is set tosuch a dimension in which at least the recess portion 17 penetrates thefirst layer 11 and the surface of the second layer 12 is exposed in therecess portion 17. To be noted, the recess portion 17 formed in thepreform 10 having the two-layer structure may be distinguished from arecess portion (described later) formed only in the first layer 11 andmay be referred to as a second recess portion. In addition, the crosssection of the recess portion 17 may be a circular shape, an ellipticalshape, a polygonal shape, a slit shape, or a shape in which these shapesare combined.

<Configuration Example of Delamination Container>

Next, a configuration example of the delamination container 20 formedfrom resin according to the first embodiment will be described withreference to FIG. 2 . FIG. 2 is a longitudinal section view of thedelamination container 20 of the first embodiment.

The delamination container 20 is a bottle-shaped resin containerobtained by performing stretch blow molding of the preform 10, andcontains, for example, a seasoning liquid such as soy sauce. To benoted, the delamination container 20 may be used to store other contentssuch as a cosmetic liquid of cosmetic products.

Similarly to the preform 10, the delamination container 20 has atwo-layer structure in which the second layer 12 is formed on the insideof the first layer 11. In a body portion 22 of the delaminationcontainer 20, a ratio (t11/t12) of a thickness t11 of the first layer 11to a thickness t12 of the second layer 12 is substantially similar tothe ratio (t1/t2) of the thickness in the body portion 14 of the preform10.

The delamination container 20 includes a neck portion 21 having anopening at an upper end thereof, a cylindrical body portion 22continuous from the neck portion 21, and a bottom portion 23 continuousfrom the body portion 22. In the manufacture of the delaminationcontainer 20, the body portion 14 and the bottom portion 15 of thepreform 10 are expanded by stretch blow to be shaped into the bodyportion 22 and the bottom portion 23 of the delamination container 20.In addition, at the time of the stretch blow, the recess portion 17 ofthe preform 10 is stretched, and thus an air introduction hole 24penetrating the first layer 11 is formed in the bottom portion 23 of thedelamination container 20.

In the delamination container 20, the space inside the second layer 12is filled with the contents. In the delamination container 20, when thecontents are discharged from the second layer 12, the air graduallyflows into a space between the first layer 11 and the second layer 12from the air introduction hole 24, and the first layer 11 and the secondlayer 12 are peeled off. As a result, the volume occupied by thecontents in the container can be replaced with air without bringing thecontents of the second layer 12 into contact with air, and the contentsfilled into the second layer 12 can be discharged to the outside of thecontainer.

In addition, similarly to the preform 10, an opening portion 25(non-laminated portion, single layer portion) penetrating the firstlayer 11 is formed at the center of the bottom portion 23 of thedelamination container 20. The opening portion 25 is filled with thematerial of the second layer 12 to close the opening portion 25, and thesecond layer 12 is exposed to the outside of the first layer 11 in thevicinity of the opening portion 25 of the bottom portion 23 of thedelamination container 20. In addition, at the bottom portion 23 of thedelamination container 20, a locking portion 26 (bulging portion 26) ofthe second layer 12 protruding outward in the radial direction from theopening portion 25 of the first layer 11 is formed. The locking portion26 is formed by stretching the locking portion 19 of the preform 10.When the second layer 12 is exposed to the outside of the first layer 11at the opening portion 25 of the delamination container 20, the secondlayer 12 is partially fixed to the first layer 11, and misalignment ofthe second layer 12 with respect to the first layer 11 is suppressed.

<Description of Manufacturing Apparatus for Delamination Container>

FIG. 3 is a diagram schematically illustrating a configuration of a blowmolding apparatus 30 according to the first embodiment. The blow moldingapparatus 30 of the first embodiment is an example of a manufacturingapparatus for the delamination container 20, and employs a hot parisonmethod (also referred to as a one-stage method) in which thedelamination container 20 is blow-molded by utilizing residual heat(internal heat amount) from injection molding without cooling thepreform 10 to room temperature.

The blow molding apparatus 30 includes a first injection molding unit31, a first temperature adjustment unit 32, a second injection moldingunit 33, a second temperature adjustment unit 34, a blow molding unit35, a taking-out unit 36, and a conveyance mechanism 37. The firstinjection molding unit 31, the first temperature adjustment unit 32, thesecond injection molding unit 33, the second temperature adjustment unit34, the blow molding unit 35, and the taking-out unit 36 are disposed atpositions rotated by the same predetermined angle (for example, 60degrees) about the conveyance mechanism 37. To be noted, the blowmolding apparatus 30 may omit the first temperature adjustment unit 32(in this case, each molding station is disposed at a position rotated by72 degrees about the conveyance mechanism 37). In addition, in the firstinjection molding unit 31 and the second injection molding unit 33, anunillustrated core mold elevation mechanism is provided above theconveyance mechanism 37.

(Conveyance Mechanism 37)

The conveyance mechanism 37 includes a rotating plate (transfer plate)37 a that rotates about a shaft in a direction perpendicular to thepaper surface of FIG. 3 . On the rotating plate 37 a, one or more neckmolds 37 b (not illustrated in FIG. 3 ) for holding the neck portion 13of the preform 10 (or the neck portion 21 of the delamination container20) are arranged at each predetermined angle. The conveyance mechanism37 rotates the rotating plate 37 a to convey the preform 10 (or thedelamination container 20) held by the neck mold 37 b to the firstinjection molding unit 31, the first temperature adjustment unit 32, thesecond injection molding unit 33, the second temperature adjustment unit34, the blow molding unit 35, and the taking-out unit 36 in this order.To be noted, the conveyance mechanism 37 can also move up and down therotating plate 37 a, and also performs operations related to moldclosing and mold opening (mold releasing) in the first injection moldingunit 31 and the second injection molding unit 33.

(First Injection Molding Unit 31)

The first injection molding unit 31 includes a cavity mold 40, a coremold 41, and a hot runner mold 42, and manufactures the first layer 11of the preform 10 in cooperation with the neck mold 37 b conveyed at thetime of molding. The cavity mold 40 includes a first cavity mold 40A onthe opening side (upper side) and a second cavity mold 40B on the bottomsurface side (lower side). A first injection device 38 that supplies afirst resin material to the hot runner mold 42 is connected to the firstinjection molding unit 31. The cavity mold 40 and the hot runner mold 42are fixed to a machine base of the blow molding apparatus 30 in anintegrated state. The core mold 41 is fixed to a core mold elevationmechanism.

FIGS. 4A and 4B illustrate the first injection molding unit 31 thatmolds the first layer 11 of the preform 10 of the first embodiment. FIG.5A is a diagram illustrating the vicinity of the bottom portion of thefirst layer 11 in the first injection molding unit 31 of the firstembodiment. FIG. 6A is a perspective view illustrating a configurationexample of the cavity mold 40 (second cavity mold 40B) of the firstinjection molding unit 31.

The cavity mold 40 defines (determines) the shape of the outer peripheryof the first layer 11. The first cavity mold 40A is a mold facing theopening side of the cavity mold 40 (the side in contact with the neckmold 37 b when the mold is closed), and defines the shape of the outerperiphery of the body portion of the first layer 11. The second cavitymold 40B is a mold facing the bottom surface side (the side in contactwith the hot runner mold 42) of the cavity mold 40, and defines theshape of the outer periphery of the bottom portion of the first layer11. The second cavity mold 40B further includes a gate portion 40Ba thatguides the resin material from the hot runner mold 42 to the cavitysurface. In addition, the hot runner mold 42 includes a resin supplyportion 42 a (resin flow path 42 a) that introduces the first resinmaterial plasticized (melted) by the first injection device 38 into thesecond cavity mold 40B. The core mold 41 is a mold that defines theshape of the inner peripheral side of the first layer 11, and isinserted into the inner peripheral side of the cavity mold 40 fromabove. The neck mold 37 b defines the outer shape of the neck portion 13of the preform 10 (first layer 11).

As illustrated in FIGS. 4A and 4B, in the first injection molding unit31, the cavity mold 40, the core mold 41, and the neck mold 37 b of theconveyance mechanism 37 are closed to form a mold space for the firstlayer 11. Then, the first resin material is poured from the bottomportion of the mold space described above through the hot runner mold42, and thus the first layer 11 of the preform 10 is manufactured in thefirst injection molding unit 31.

A first protrusion portion 44 having a columnar shape, a taperedcolumnar shape, a prismatic shape, or the like is provided at apredetermined position on the upper surface side (cavity surface side)of the second cavity mold 40B facing the outer periphery of the bottomportion of the first layer 11. As illustrated in FIG. 6A, at least onefirst protrusion portion 44 is disposed at an interval in the radialdirection from the center of the bottom portion where the resin supplyportion 42 a is located. As illustrated in FIG. 5A, a protrusion amounth1 of the first protrusion portion 44 from the cavity standard surfaceof the second cavity mold 40B (the cavity surface that defines the shapeof the lower end side of the outer peripheral surface of the bottomportion of the first layer 11) is substantially the same dimension asthe thickness of the first layer 11. Therefore, when the molds of thefirst injection molding unit 31 are closed, the distal end of the firstprotrusion portion 44 faces the surface of the core mold 41 (disposed inthe vicinity of the surface of the core mold 41). As a result, in theinjection molding of the first injection molding unit 31, a recessportion 11 a such as a circular shape is formed in the first layer 11 ata position corresponding to the recess portion 17 of the preform 10 bythe first protrusion portion 44. The recess portion 11 a of the firstlayer 11 may penetrate the first layer 11, or may have a thin filmformed between the core mold 41 and the first protrusion portion 44. Tobe noted, the recess portion 11 a of the first layer 11 formed by thefirst injection molding unit 31 is also referred to as a first recessportion.

In addition, as illustrated in FIG. 4B, the resin supply portion 42 a ofthe hot runner mold 42 is provided with a valve pin (a bar-shaped memberthat opens and closes the resin supply portion 42 a) 43 that is movablein the axial direction to a position close to the core mold 41. Thevalve pin 43 is accommodated in the hot runner mold 42 until the moldspace is filled with the first resin material, and protrudes to aposition closer to the core mold 41 than the opening end on the cavityside of the gate portion 40Ba after the mold space is filled with thefirst resin material. By such movement of the valve pin 43 duringinjection molding, a thin film portion 18 in which the thickness of theresin material is smaller than that of the peripheral portion can beformed at the center of the bottom portion of the first layer 11.

In addition, even when the molds of the first injection molding unit 31are opened, the neck mold 37 b of the conveyance mechanism 37 keeps onholding and conveying the first layer 11 of the preform 10 withoutopening. The number of the preforms 10 simultaneously molded by thefirst injection molding unit 31 (that is, the number of the delaminationcontainers 20 that can be simultaneously molded by the blow moldingapparatus 30) can be appropriately set.

(First Temperature Adjustment Unit 32)

The first temperature adjustment unit 32 includes an unillustratedtemperature adjustment mold (a heating pot or a temperature adjustmentpot (conditioning pot) that adjusts the temperature of the first layer11 from the outside, and a heating rod, a temperature adjustment rod(conditioning rod), or an air introduction rod that adjusts thetemperature of the first layer 11 from the inside). The firsttemperature adjustment unit 32 cools (or heats) the first layer 11 in ahigh-temperature state after injection molding by accommodating thefirst layer 11 in the temperature adjustment mold maintained at apredetermined temperature. In addition, the first temperature adjustmentunit 32 also has a function of adjusting the temperature distribution ofthe first layer 11 to a predetermined state before being conveyed to thesecond injection molding unit 33.

(Second Injection Molding Unit 33)

The second injection molding unit 33 includes a cavity mold 50, a coremold 51, and a hot runner mold 52, and performs injection molding of thesecond layer 12 on the inner peripheral side of the first layer 11 incooperation with the neck mold 37 b conveyed at the time of molding. Thecavity mold 50 includes a first cavity mold 50A on the opening side(upper side) and a second cavity mold 50B on the bottom surface side(lower side). A second injection device 39 that supplies a second resinmaterial to the hot runner mold 52 is connected to the second injectionmolding unit 33.

FIG. 4C illustrates the second injection molding unit 33 that molds thesecond layer 12 of the preform 10. FIG. 5B is a diagram illustrating thevicinity of the bottom portion of the preform 10 in the second injectionmolding unit 33.

The cavity mold 50 is a mold that accommodates the first layer 11. Thefirst cavity mold 50A is a mold facing the opening side of the cavitymold 50, and accommodates the body portion of the first layer 11. Thesecond cavity mold 50B is a mold facing the bottom surface side of thecavity mold 50, and accommodates the bottom portion of the first layer11. The second cavity mold 50B further includes a gate portion 50Ba thatguides the resin material from the hot runner mold 52 to the cavitysurface. In addition, the hot runner mold 52 includes, at the center ofthe bottom portion, a resin supply portion 52 a (resin supply path 52 a)that introduces the second resin material plasticized (melted) by thesecond injection device 39. The core mold 51 is a mold that defines theshape of the inner peripheral side of the second layer 12, and isinserted into the inner peripheral side of the cavity mold 50 fromabove. The neck mold 37 b defines an upper end surface (top surface) ofthe neck portion 13 of the preform 10 (second layer 12). Note that thehot runner mold 52 may have a structure including a valve pin like thehot runner mold 42. However, the position of the valve pin when closingthe second resin material is set to a position not protruding from theopening end on the cavity side of the gate portion 50Ba.

As illustrated in FIG. 4C, the second injection molding unit 33accommodates the first layer 11 of the preform 10 injection-molded bythe first injection molding unit 31. In a state where the secondinjection molding unit 33 is closed, a mold space is formed between theinner peripheral side of the first layer 11 and the surface of the coremold 51. In the second injection molding unit 33, the second resinmaterial is poured from the bottom portion of the mold space describedabove through the hot runner mold 52 to form the preform 10 in which thesecond layer 12 is formed on the inner peripheral side of the firstlayer 11.

In addition, on the upper surface side (cavity surface side) of thesecond cavity mold 50B facing the outer periphery of the bottom portionof the first layer 11, a second protrusion portion 54 having a columnarshape or the like corresponding to the shape of the recess portion 17 ofthe preform 10 is provided at a predetermined position corresponding tothe first protrusion portion 44 of the first injection molding unit 31.The second protrusion portion 54 is inserted into the recess portion 11a of the first layer 11 when the first layer 11 is accommodated in thesecond injection molding unit 33. As described above, the basicconfiguration of the protrusion and the like in the second cavity mold50B is substantially similar to that of the second cavity mold 40B ofthe first injection molding unit 31.

Here, as illustrated in FIG. 5B, a protrusion amount h2 of the secondprotrusion portion 54 from the cavity standard surface of the secondcavity mold 50B (the cavity surface in contact with a lower end sideregion of the outer peripheral surface of the bottom portion of thefirst layer 11) is a larger dimension than the thickness of the firstlayer 11. That is, the protrusion amount h2 of the second protrusionportion 54 is larger than the protrusion amount h1 of the firstprotrusion portion 44 (h2>h1). Therefore, when the second injectionmolding unit 33 is closed, the distal end of the second protrusionportion 54 penetrates the recess portion 11 a of the first layer 11 andprotrudes to the inner peripheral side of the first layer 11. Byproviding the second protrusion portion 54 in the second cavity mold 50Bof the second injection molding unit 33, the recess portion 17 can beformed in the bottom portion 15 of the preform 10.

In addition, the protrusion amount h2 of the second protrusion portion54 is set to be smaller than the thickness of the preform 10. That is,in the injection molding in the second injection molding unit 33, sincethe second resin material flows into a space between the core mold 51and the second protrusion portion 54, a hole penetrating the secondlayer 12 is not formed by the second protrusion portion 54.

In addition, as illustrated in FIG. 5B, in the cavity mold 50, a cavityend portion 53 connected to the gate portion 50Ba is formed with anenlarged diameter portion (bulging portion) expanding toward the moldspace and having a curved surface shape. Therefore, in the vicinity ofthe center of the bottom portion of the second injection molding unit33, a gap is generated between the curved surface of the cavity endportion 53 of the cavity mold 50 and the outer peripheral surface of thefirst layer 11. The second resin material flows into the gap describedabove during injection molding. As a result, the locking portion 19protruding outward in the radial direction from the opening portion 16can be integrally formed with the second layer 12 on the outside of thefirst layer 11.

(Second Temperature Adjustment Unit 34)

The second temperature adjustment unit 34 includes an unillustratedtemperature adjustment mold unit (a heating pot or a temperatureadjustment pot (conditioning pot) that adjusts the temperature of thepreform 10 from the outside, and a heating rod, a temperature adjustmentrod (conditioning rod), or an air introduction rod that adjusts thetemperature of the preform 10 from the inside). The second temperatureadjustment unit 34 accommodates the preform 10 conveyed from the secondinjection molding unit 33 in a mold unit maintained at a predeterminedtemperature to equalize temperature and remove temperature unevenness,and adjusts the temperature of the preform 10 to a temperature suitablefor final blowing (for example, about 90° C. to 105° C.). In addition,the second temperature adjustment unit 34 also has a function of coolingthe preform 10 in a high temperature state after injection molding.

(Blow Molding Unit 35)

The blow molding unit 35 performs blow molding on the preform 10 whosetemperature has been adjusted by the second temperature adjustment unit34 to manufacture the delamination container 20.

The blow molding unit 35 includes a blow cavity mold which is a pair ofsplit molds corresponding to the shape of the delamination container 20,a bottom mold, a stretching rod, and an air introduction member (all notillustrated). The blow molding unit 35 blow-molds the preform 10 whilestretching the preform 10. As a result, the preform 10 is shaped intothe shape of the blow cavity mold, and the delamination container 20 canbe manufactured.

(Taking-Out Unit 36)

The taking-out unit 36 is configured to release the neck portion 21 ofthe delamination container 20 manufactured by the blow molding unit 35from the neck mold 37 b and take out the delamination container 20 tothe outside of the blow molding apparatus 30.

<Description of Manufacturing Method for Container>

Next, a manufacturing method for the delamination container 20 by theblow molding apparatus 30 of the first embodiment will be described.FIG. 7 is a flowchart illustrating steps of the manufacturing method forthe delamination container 20.

(Step S101: First Injection Molding Step)

First, as illustrated in FIG. 4A, in the first injection molding unit31, the first resin material is injected from the first injection device38 into the mold space formed by the cavity mold 40, the core mold 41,and the neck mold 37 b, and the first layer 11 of the preform 10 isformed. At this time, the first protrusion portion 44 forms the recessportion 11 a at the bottom portion of the first layer 11.

In the first injection molding unit 31, as illustrated in FIG. 4B, afterthe first layer 11 of the preform 10 is formed, a step of protruding thevalve pin 43 to a position close to the core mold 41 is performed. As aresult, the thin film portion 18 having a thickness smaller than that ofthe peripheral portion is formed at the center of the bottom portion ofthe first layer 11.

Thereafter, the molds of the first injection molding unit 31 are openedto release the first layer. When the molds of the first injectionmolding unit 31 are opened, the rotating plate 37 a of the conveyancemechanism 37 rotates by a predetermined angle, and the first layer 11 ofthe preform 10 held by the neck mold 37 b is conveyed to the firsttemperature adjustment unit 32 in a state of having residual heat frominjection molding.

(Step S102: First Temperature Adjustment Step)

Next, in the first temperature adjustment unit 32, the first layer 11 ofthe preform 10 is accommodated in the temperature adjustment mold, andcooling of the first layer 11 and adjustment of the temperaturedistribution (temperature equalization and removal of temperatureunevenness) are performed. To be noted, the first temperature adjustmentstep may be omitted.

After the first temperature adjustment step (or the first injectionmolding step), the rotating plate 37 a of the conveyance mechanism 37rotates by a predetermined angle, and the first layer 11 havingundergone temperature adjustment and held in the neck mold 37 b isconveyed to the second injection molding unit 33.

(Step S103: Second Injection Molding Step)

Subsequently, the first layer 11 of the preform 10 is accommodated inthe second injection molding unit 33, and injection molding of thesecond layer 12 is performed.

In the second injection molding unit 33, as illustrated in FIG. 4C, amold space is formed between the inner peripheral side of the firstlayer 11 and the surface of the core mold 51 facing the inner peripheryof the first layer 11, and the second resin material is injected intothe mold space described above from the hot runner mold 52. To be noted,although the thin film portion 18 is formed at the bottom portion of thefirst layer 11, the thin film portion 18 is broken by the injectionpressure of the second resin material to form an opening portion 16 atthe bottom portion, and the second resin material is guided from theopening portion 16 to the inner peripheral side of the first layer 11.

Here, the temperature of the second resin material injected in thesecond injection molding unit 33 is set to a temperature lower than themelting point of the first resin material. In addition, the surfacetemperature of the first layer 11 when the second resin material isinjected in the second injection molding unit 33 is cooled to atemperature equal to or lower than the melting point of the second resinmaterial.

In the second injection molding unit 33, the cavity mold 50 faces theouter peripheral side of the first layer 11, and the shape of the firstlayer 11 is held by the cavity mold 50 from the outer peripheral side.Therefore, even when the second resin material comes into contact withfirst layer 11, thermal deformation of first layer 11 can be suppressed.

In addition, in the second injection molding unit 33, since the secondprotrusion portion 54 penetrates and closes the recess portion 11 a ofthe first layer 11, the recess portion 17 of the preform 10 is notclosed by the second resin material. In addition, since the distal endof the second protrusion portion 54 in the second injection molding unit33 protrudes to the inner peripheral side of the first layer, the recessportion 17 of the preform 10 formed by the second protrusion portion 54has a shape that penetrates the first layer 11 and the surface of thesecond layer 12 is exposed in the recess portion 17.

In addition, in the second injection molding unit 33, the lockingportion 19 is integrally formed with the second layer 12 on the outsideof the first layer 11 by allowing the second resin material to flow intothe gap between the curved surface of the cavity end portion 53 adjacentto the gate portion 50Ba of the cavity mold 50B and the outer peripheralsurface of the first layer 11. The locking portion 19 is caught on theoutside of the first layer 11, and thus the second layer 12 is preventedfrom slipping out from the first layer 11.

As described above, the preform 10 in which the second layer 12 isformed on the inner peripheral side of the first layer 11 ismanufactured by the first injection molding step and the secondinjection molding step.

Thereafter, when the molds of the second injection molding unit 33 areopened, the rotating plate 37 a of the conveyance mechanism 37 rotatesby a predetermined angle, and the preform 10 held by the neck mold 37 bis conveyed to the second temperature adjustment unit 34 in a state ofhaving residual heat from injection molding.

(Step S104: Second Temperature Adjustment Step)

Subsequently, in the second temperature adjustment unit 34, the preform10 is accommodated in the temperature adjustment mold unit, andtemperature adjustment for bringing the temperature of the preform 10closer to a temperature suitable for final blowing is performed.Thereafter, the rotating plate 37 a of the conveyance mechanism 37rotates by a predetermined angle, and the preform 10 having undergonetemperature adjustment and held in the neck mold 37 b is conveyed to theblow molding unit 35.

(Step S105: Blow Molding Step)

Subsequently, in the blow molding unit 35, blow molding of thedelamination container 20 is performed.

First, the blow cavity mold is closed to accommodate the preform 10 inthe mold space, and the air introduction member (blow core) is lowered,so that the air introduction member abuts the neck portion 13 of thepreform 10. Then, the stretching rod is lowered to press the bottomportion 15 of the preform 10 from the inside, and blow air is suppliedfrom the air introduction member while performing longitudinal axisstretching as necessary, and thus the preform 10 is stretched in thelateral axis. As a result, the preform 10 is shaped by being bulged soas to be in close contact with the mold space of the blow cavity mold,and is thus blow-molded into the delamination container 20.

(Step S106: Container Take-out Step)

When the blow molding is completed, the blow cavity mold is opened. As aresult, the delamination container 20 becomes movable from the blowmolding unit 35.

Subsequently, the rotating plate 37 a of the conveyance mechanism 37rotates by a predetermined angle, and the delamination container 20 isconveyed to the taking-out unit 36. In the taking-out unit 36, the neckportion 21 of the delamination container 20 is released from the neckmold 37 b, and the delamination container 20 is taken out to the outsideof the blow molding apparatus 30.

Thus, one cycle in the manufacturing method for the delaminationcontainer ends. Thereafter, by rotating the rotating plate 37 a of theconveyance mechanism 37 by a predetermined angle, the respective stepsof S101 to S106 described above are repeated. To be noted, during theoperation of the blow molding apparatus 30, six sets of the delaminationcontainers 20 are manufactured in parallel at a time difference of onestep each.

In addition, due to the structure of the blow molding apparatus 30, thewaiting times of the first injection molding step, the first temperatureadjustment step, the second injection molding step, the secondtemperature adjustment step, the blow molding step, and the containertake-out step are the same. Similarly, the conveyance times between thesteps are also the same.

Hereinafter, effects of the blow molding apparatus and the blow moldingmethod of the first embodiment will be described.

In the first embodiment, the first layer 11 (outer layer) of the preform10 is molded in the first injection molding step, and the second layer12 (inner layer) is injection-molded on the inside of the first layer 11from the opening portion 16 of the first layer 11 in the secondinjection molding step to manufacture the preform 10 having a two-layerstructure. According to the first embodiment, the outer layer can befirst formed from a resin material having a high melting point, and thenthe inner layer can be formed from a resin material having a meltingpoint lower than that of the outer layer. That is, the injection moldingof the inner layer can be continuously performed while the outer layerhas the residual heat from the injection molding, so that the preform 10having the two-layer structure suitable for the specification of thedelamination container 20 can be manufactured. In the first embodiment,since the preform 10 having a two-layer structure is released in a statewhere both the outer layer and the inner layer have residual heat forminjection molding, it is possible to obtain the preform 10 suitable formanufacturing the delamination container 20 by a blow molding method ofa hot parison type.

Further, in the first embodiment, the preform 10 having the two-layerstructure described above is subjected to stretch blow molding in astate where the preform 10 has the residual heat from injection moldingto manufacture the delamination container 20. Therefore, in the firstembodiment, the delamination container 20 having excellent aestheticappearance, physical property strength, and the like can be manufacturedby a blow molding method of a hot parison type. As compared with blowmolding of a cold parison type, in the first embodiment, it is notnecessary to cool the produced preform 10 to near room temperature, andthe step of reheating the preform 10 is also unnecessary. Therefore,according to the first embodiment, a series of steps from injectionmolding of the preform 10 to blow molding of the delamination container20 can be completed in a relatively short time, and the delaminationcontainer 20 can be manufactured in a shorter cycle.

In addition, in the first embodiment, in the second injection moldingstep, the locking portion 19 is integrally formed on the outer side ofthe first layer 11 from the second resin material forming the secondlayer 12, and the second layer 12 is prevented from coming off from thefirst layer 11.

As a result, when a force in the pull-out direction acts on the secondlayer 12 toward the neck portion, the locking portion 19 abuts the firstlayer 11 to become a resistance to the force in the pull-out direction,and thus the outer layer and the inner layer of the preform 10 are lesslikely to deviate from each other. Therefore, in the first embodiment,for example, it is possible to suppress unintended separation andmisalignment between the outer layer and the inner layer at the time ofpulling out the core mold in the second injection molding step, the blowmolding step, or the like, and it is possible to improve the productionyield of the delamination container 20.

Second Embodiment

Next, a second embodiment will be described. In the followingdescription, elements similar to those of the first embodiment aredenoted by the same reference numerals, and redundant description willbe omitted.

For example, in a case where the outer layer is molded first and theinner layer is molded later when a preform having a two-layer structureis molded, if the resin material of the inner layer to be injected laterunintentionally wraps around the outer peripheral side to cover theouter side of the preform, the aesthetic appearance of the containerafter blow molding is greatly impaired.

In the second embodiment, a configuration for suppressing a moldingdefect in which the resin material of the inner layer unintentionallywraps around the outer peripheral side when the delamination containeris manufactured by applying a blow molding method of a hot parison typewill be described.

FIG. 8 is a longitudinal section view of a preform 10 of the secondembodiment. Hereinafter, differences between the preform 10 of the firstembodiment illustrated in FIG. 1 and the second embodiment will bedescribed. In the bottom portion 15 of the preform 10 of the secondembodiment illustrated in FIG. 8 , a raised portion 12 a protruding in acurved surface shape is formed on the inner peripheral side of thesecond layer 12. The raised portion 12 a is a resin reservoir formed atthe time of injection molding of the second resin material, and isformed at a position facing the opening portion 16 of the first layer11.

Note that the configuration of the delamination container 20 in thesecond embodiment is similar to that in the first embodiment, and thusredundant description will be omitted.

In addition, a basic configuration of the blow molding apparatus 30 ofthe second embodiment is similar to that of the blow molding apparatus30 of the first embodiment illustrated in FIG. 3 . Hereinafter,differences in the second embodiment will be described.

FIGS. 9A to 9C are diagrams illustrating a manufacturing process of thepreform of the second embodiment. FIG. 10A is a diagram illustrating thevicinity of the bottom portion of the first layer in a first injectionmolding portion of the second embodiment, and FIG. 10B is a diagramillustrating the vicinity of the bottom portion of the preform in asecond injection molding portion of the second embodiment. FIGS. 9A to9C correspond to FIGS. 4A to 4C of the first embodiment, and FIGS. 10Ato 10B correspond to FIGS. 5A to 5B of the first embodiment.

In the first injection molding unit 31 of the second embodiment, asillustrated in FIG. 9A, the length of the inner peripheral portion ofthe cavity mold 40 in the axial direction corresponding from the upperend of the body portion to the bottom surface of the first layer 11 isset to L1.

In addition, in the second injection molding unit 33 of the secondembodiment, as illustrated in FIG. 9C, the length (depth) in the axialdirection of the inner peripheral portion of the cavity mold 50 thataccommodates the upper end of the body portion and the bottom surface ofthe first layer 11 is set to L2 smaller than L1 (L1>L2). For example, L2is set to be smaller than L1 by a deformation margin (corresponding tocompression of the first layer 11 caused by pushing up of the cavitymold 50 or shrinkage of the first layer 11 caused by heat dissipation orthe like before the second injection molding step) of the first layer11. That is, the depth of the mold space of the cavity mold 50accommodating the first layer 11 is smaller than the length of the firstlayer 11 in the axial direction.

As illustrated in FIGS. 9C and 10B, a concave portion 51 a having acurved surface shape is formed at a distal end portion of a core mold 51in the second embodiment. When the molds are closed, the concave portion51 a faces the outlet of the second resin material located at the centerof the second cavity mold 50B, and forms a space of a resin reservoirwith the opening portion 16 of the first layer 11. This resin reservoirforms the raised portion 12 a on the inner peripheral side of the secondlayer 12.

In addition, as illustrated in FIG. 10B, for example, in the secondinjection molding unit 33 of the second embodiment, an opening diameterd2 (the diameter of the valve pin) of the distal end of the hot runnermold 52 is set to be smaller than the opening diameter (the diameter ofthe valve pin 43) of the distal end of the hot runner mold 42 of thefirst injection molding unit 31 and a diameter d1 of the opening portion16 of the first layer 11. By reducing the opening diameter d2 of thedistal end of the hot runner mold 52 to be smaller than the diameter d1of the opening portion 16, the flow velocity of the second resinmaterial injected into the mold space of the second injection moldingunit 33 can be increased.

As illustrated in FIG. 7 , the steps of the manufacturing method for thedelamination container 20 in the second embodiment include a firstinjection molding step (S101), a first temperature adjustment step(S102), a second injection molding step (S103), a second temperatureadjustment step (S104), a blow molding step (S105), and a containertake-out step (S106). The first injection molding step (S101) and thefirst temperature adjustment step (S102) of the second embodiment aresimilar to those of the first embodiment.

In the second injection molding step (S103) of the second embodiment,the first layer 11 of the preform 10 is accommodated in the secondinjection molding unit 33, and injection molding of the second layer 12is performed.

In the second injection molding unit 33, as illustrated in FIG. 9C, amold space is formed between the inner peripheral side of the firstlayer 11 and the surface of the core mold 51 facing the inner peripheryof the first layer 11, and the second resin material is injected intothe mold space described above from the hot runner mold 52. To be noted,although the thin film portion 18 is formed at the bottom portion of thefirst layer 11, the thin film portion 18 is broken by the injectionpressure of the second resin material to form an opening portion 16 atthe bottom portion, and the second resin material is guided from theopening portion 16 to the inner peripheral side of the first layer 11.

As described above, the depth of the mold space of the cavity mold 50accommodating the first layer 11 is smaller than the length of the firstlayer 11 in the axial direction. Therefore, when the first layer 11 isaccommodated in the cavity mold 50, the bottom portion of the firstlayer 11 is pressed against and thus brought into contact with thebottom surface of the cavity mold 50, so that it is possible to suppressgeneration of a gap between the bottom portion of the first layer 11 andthe cavity mold 50.

In addition, a space of a resin reservoir is formed between the openingportion 16 of the first layer 11 and the concave portion 51 a of thecore mold 51. The second resin material that has passed through theopening portion 16 hits the concave portion 51 a of the core mold 51 andis agitated in the space of the resin reservoir, and then flows into themold space between the inner periphery of the first layer 11 and thesurface of the core mold 51. As the second resin material is agitated inthe space of the resin reservoir, fragments of the thin film portion 18of the first layer 11 are mixed with the high-temperature second resinmaterial and melted. This makes it possible to dissipate the fragmentsof the thin film portion 18 to such an extent as to be visuallyunrecognizable.

In addition, the opening diameter d2 of the distal end of the hot runnermold 52 is reduced to be smaller than the diameter d1 of the openingportion 16 of the first layer 11. By increasing the flow velocity of thesecond resin material until the second resin material passes through thedistal end of the hot runner mold 52 and hits the concave portion 51 a,sufficient agitation of the second resin material is caused in the spaceof the resin reservoir, and the fragments of the thin film portion 18can be more easily dissipated. Furthermore, the thin film portion 18 canbe more easily broken.

To be noted, part of the second resin material is guided to the outsideof first layer 11 through opening portion 16 after hitting the concaveportion 51 a, and circulates in the vicinity of opening portion 16. Sucha flow also agitates the second resin material to promote thedissipation of the fragments of the thin film portion 18.

Here, the temperature of the second resin material injected in thesecond injection molding unit 33 is set to a temperature lower than themelting point of the first resin material. In addition, the surfacetemperature of the first layer 11 when the second resin material isinjected in the second injection molding unit 33 is cooled to atemperature equal to or lower than the melting point of the second resinmaterial.

In the second injection molding unit 33, the cavity mold 50 faces theouter peripheral side of the first layer 11, and the shape of the firstlayer 11 is held by the cavity mold 50 from the outer peripheral side.Therefore, even when the second resin material comes into contact withfirst layer 11, thermal deformation of first layer 11 can be suppressed.

In addition, in the second injection molding unit 33, since the secondprotrusion portion 54 penetrates and closes the recess portion 11 a ofthe first layer 11, the recess portion 17 of the preform 10 is notclosed by the second resin material. In addition, since the distal endof the second protrusion portion 54 in the second injection molding unit33 protrudes to the inner peripheral side of the first layer, the recessportion 17 of the preform 10 formed by the second protrusion portion 54has a shape that penetrates the first layer 11 and the surface of thesecond layer 12 is exposed in the recess portion 17.

As described above, the preform 10 in which the second layer 12 isformed on the inner peripheral side of the first layer 11 ismanufactured by the first injection molding step and the secondinjection molding step.

Thereafter, when the molds of the second injection molding unit 33 areopened, the rotating plate 37 a of the conveyance mechanism 37 rotatesby a predetermined angle, and the preform 10 held by the neck mold 37 bis conveyed to the second temperature adjustment unit 34 in a state ofhaving residual heat from injection molding.

To be noted, the second temperature adjustment step (S104), the blowmolding step (S105), and the container take-out step (S106) of thesecond embodiment are similar to those of the first embodiment.

Hereinafter, effects of the blow molding apparatus and the blow moldingmethod of the second embodiment will be described.

In the second embodiment, in the second injection molding unit 33, thedepth of the mold space of the cavity mold 50 accommodating the firstlayer 11 is smaller than the length of the first layer 11 in the axialdirection. Therefore, the bottom portion of the first layer 11 ispressed against the bottom surface of the cavity mold 50, and generationof a gap between the bottom portion of the first layer 11 and the cavitymold 50 is suppressed. Therefore, according to the present embodiment,the second resin material is less likely to flow into a space betweenthe first layer 11 and the cavity mold 50, and occurrence of the moldingdefect in which the second resin material covers the outer periphery ofthe first layer 11 is suppressed.

In addition, in the second embodiment, the concave portion 51 a isprovided at the distal end portion of the core mold 51, and thefragments of the thin film portion 18 are mixed and melted by beingagitated with the high-temperature second resin material duringinjection molding, so that the fragments of the thin film portion 18 areeasily dissipated. As a result, in the preform 10 and the delaminationcontainer 20, it is possible to reduce the possibility that theaesthetic appearance is impaired due to the fragments of the thin filmportion 18 remaining in the inner layer.

The present invention is not limited to the above embodiment, andvarious improvements and design changes may be made without departingfrom the gist of the present invention.

In the above embodiment, an example in which one recess portion 17 isprovided in the bottom portion 15 of the preform 10 has been described,but for example, a plurality of recess portions 17 may be formed. FIG.6B illustrates an example in which the first protrusion portions 44 areprovided at two positions in the second cavity mold 40B of the firstinjection molding unit 31. In the example of FIG. 6B, the two firstprotrusion portions 44 are arranged at point-symmetrical positions withrespect to the central axis at an interval of 180°. To be noted, thenumber of the first protrusion portions 44 may be three or more. In thiscase, it is preferable that the first protrusion portions 44 arearranged in a point-symmetric positional relationship with respect tothe central axis.

According to the above configuration, the unevenness of the flow of theresin in the circumferential direction during the injection molding isfurther reduced. To be noted, in the case of the above configuration, itis also necessary to arrange second protrusion portions 54 at positionssimilar to the first protrusion portions 44 also in the second injectionmolding unit 33.

In addition, the embodiment disclosed herein should be considered in allrespects as illustrative and not restrictive. The scope of the presentinvention is indicated not by the above description but by the claims,and it is intended that meanings equivalent to the claims and allmodifications within the scope are included.

What is claimed is:
 1. A manufacturing method for a delaminationcontainer, the manufacturing method comprising: injection-molding afirst layer of a preform having a bottomed cylindrical shape from afirst resin material as a first injection molding; injecting a secondresin material different from the first resin material to form a secondlayer on an inner peripheral side of the first layer as a secondinjection molding; and blow-molding, in a state of having residual heatfrom injection molding, the preform obtained during the second injectionmolding, to manufacture the delamination container, wherein, during thesecond injection molding, the second resin material is guided from anopening portion formed in the first layer toward an inner peripheralside of the first layer, and a locking portion protruding from theopening portion toward an outer peripheral side of the first layer isintegrally formed with the second layer.
 2. The manufacturing method forthe delamination container according to claim 1, wherein, during thesecond injection molding, the first layer is accommodated in a moldspace of a first mold, a second mold is inserted into the first layer,and the second resin material is injected into a space between the firstlayer and the second mold, and a depth of the mold space of the firstmold is smaller than a length in an axial direction of the first layerobtained during the first injection molding.
 3. The manufacturing methodfor the delamination container according to claim 1, wherein, during thefirst injection molding, a thin film portion having a small thickness isformed in part of the first layer, and during the second injectionmolding, the second resin material is guided to the inner peripheralside of the first layer by breaking the thin film portion by injectionof the second resin material.
 4. The manufacturing method for thedelamination container according to claim 3, wherein, in the secondmold, a concave portion is formed at a position facing an injection portfor the second resin material.
 5. The manufacturing method for thedelamination container according to claim 4, wherein, during the secondinjection molding, a size of the injection port for the second resinmaterial is smaller than a size of an opening portion in the first layerformed by breakage of the thin film portion.
 6. The manufacturing methodfor the delamination container according to claim 1, wherein the firstresin material has a higher melting point than the second resinmaterial.
 7. A manufacturing apparatus for the delamination container,the manufacturing apparatus comprising: a first injection molding unitconfigured to injection-mold a first layer of a preform having abottomed cylindrical shape from a first resin material; a secondinjection molding unit configured to inject a second resin materialdifferent from the first resin material to form a second layer on aninner peripheral side of the first layer; and a blow molding unitconfigured to blow-mold, in a state of having residual heat frominjection molding, the preform obtained by the second injection moldingunit, to manufacture the delamination container, wherein the secondinjection molding unit guides the second resin material from an openingportion formed in the first layer toward an inner peripheral side of thefirst layer, and integrally forms a locking portion protruding from theopening portion toward an outer peripheral side of the first layer withthe second layer.
 8. The manufacturing apparatus for the delaminationcontainer according to claim 7, wherein the second injection moldingunit includes a first mold configured to accommodate the first layer ina mold space, and a second mold configured to be inserted into the firstlayer, and injects the second resin material into a space between thefirst layer and the second mold, and a depth of the mold space of thefirst mold is smaller than a length in an axial direction of the firstlayer obtained by the first injection molding unit.